[unreadable] Overweight and obesity are increasing public health concerns in the United States. A correlate of overweight and obesity, the metabolic syndrome, is a significant risk factor for cardiovascular disease, diabetes mellitus, and is a risk factor for increased all-cause mortality. Central adiposity, as measured by waist circumference or waist-hip ratio, is a key factor predisposing to the metabolic syndrome. One potential underlying pathogenic factor for the metabolic syndrome is insulin resistance. During pregnancy, insulin sensitivity is decreased, frequently leading to the development of gestational diabetes. Gestational diabetes is associated with significant increases in maternal complications and fetal morbidity, as well as being a risk factor for later development of type II diabetes mellitus. Physical activity during pregnancy may be beneficial in increasing insulin sensitivity and in managing gestational diabetes. Weight gained during pregnancy, at least in part due to increases in insulin resistance, is commonly retained after pregnancy and may lead to future overweight, obesity, and the metabolic syndrome. In men and non- pregnant women, physical activity may lead to decreases in central adiposity and improvement in insulin sensitivity. We hypothesize that increasing physical activity during pregnancy may attenuate the increases in central adiposity and the physiological decrease in insulin sensitivity during pregnancy, potentially leading to improved metabolic parameters both during and after pregnancy and improved maternal and fetal outcomes. We propose pilot studies, linked to an ongoing randomized controlled trial of exercise in pregnancy, to inform a larger study of these outcomes. The specific aims of this study are: 1) to determine whether a structured program of moderate to vigorous exercise in pregnancy leads to decreased central adiposity in the postpartum; and 2) to examine the feasibility of studying fetal outcomes in the parent randomized trial. This study will be important in finding methods to help women avoid excessive weight gain during and after pregnancy, and in reducing the long-term potential health effects of pregnancy. It may offer a safe and readily available method to control weight and improve infant health during and after pregnancy. [unreadable] [unreadable] [unreadable]